1. Field of the Invention
The subject invention relates to liquid crystal light valves (LCLV's) and more particularly to an improved light valve employing a titanium dioxide/silicon dioxide mirror and a bonding structure enabling the use of such a mirror.
2. Description of Related Art
In the prior art, liquid crystal light valves (LCLV's) are known. These devices have diverse application as light amplifiers, projectors and image processors. A prior art LCLV is disclosed in U.S. Pat. No. 4,019,807 assigned to Hughes Aircraft Company. The light valve of that patent employs successive device layers comprising a cadmium sulfide CdS photoconductor, a cadmium telluride CdTe light absorbing layer, a dielectric mirror, an insulating silicon dioxide layer, and a liquid crystal layer. This device structure is sandwiched between indium-tin-oxide transparent electrodes deposited on optical quality glass flat substrates. The particular function of the dielectric mirror is to provide several orders of magnitude of light blocking to prevent high light intensity from saturating the photoconductive layer.
One type of prior art dielectric mirror has been fabricated using a silicon/silicon dioxide (Si/SiO.sub.2) design. This mirror design has proved to have disadvantages in that it lacks repeatability, provides relatively low resolution and has an output of limited spectrum. In particular, the Si/SiO.sub.2 mirror of the prior art has been unable to operate in the blue area of the spectrum. The resistivity of Si/SO.sub.2 also limits the available resolution. In practice, it has proved difficult to produce two devices employing Si/SiO.sub.2 mirrors which have the same characteristics.
In addition, the CdS photoconductors of prior art devices, such as that of the '807 patent, exhibit a response time which is too slow for some applications such as interfacing with a video raster.
Other practical problems also confront the design of an improved LCLV structure. The foremost of these is the necessity to produce a structure in which various structural layers selected to exhibit improved properties will all adhere together well.